Given the level of bullshit in the health and fitness world—especially around diet and nutrition—let's get something straight up front: the PB6 diet isn't magic. It's just a very easy and sustainable approach to eating that has reliably helped many of our clients at A3 Health lose excess body fat and improve their health biomarkers over time.
If you're like our clients, you're smart, motivated, and already have a pretty good sense of what you "should" be eating. But you're also incredibly busy, have a ton of other priorities, travel frequently, and eat a large percentage of your meals out—often in social settings, whether for work or pleasure, where you want to eat like a normal person and enjoy yourself.
The PB6 Diet is designed with that reality in mind. It's extremely simple, doesn't require tracking or weighing or measuring, and lets you eat pretty much anything. Instead, it leverages some easy heuristic rules—built on a large body of behavioral psychology and nutritional biochemistry research—to keep you from going overboard, and to help you make slightly healthier choices over the course of your day.
As our clinical testing has demonstrated, if you stick to these rules day in and day out, you'll end up making real change, fast.
Who This Is For (And Who It's Not)
This approach works best for: busy professionals who eat out frequently, travel for work, have unpredictable schedules, and want something sustainable rather than restrictive. If you're carrying some excess body fat and want to lose it without upending your life, PB6 is built for you.
This probably isn't ideal for: competitive athletes with highly specific performance nutrition needs, people with medical conditions that require specialized diets, or anyone who wants the *most* effective approach possible rather than the most practical one. PB6 is a solid 80/20 solution—if you want the extra 20%, that requires actual testing (bloodwork, genetics, metabolic markers) and individualized programming, which is what we do at A3 but isn't something a general framework can deliver.
The Entire Diet in Four Rules
1. Fast 16 hours overnight. When you stop eating at night—whether food or calorie-containing beverages—start a timer, then don't eat again until 16 hours later. That might mean you stop eating post-dinner at 9pm, then have lunch at 1pm the next day. Or end at 10pm and start again at 2pm, or 8pm and noon. While fasting, you can (and should) still drink water, seltzer, coffee, and tea.
2. From the end of your fast until 6pm, eat Paleo. Eat Paleo-diet-friendly foods for lunch and any afternoon snacks.
Eat: meat, fish, eggs, vegetables, fruits, nuts, seeds, herbs, spices, healthy fats and oils (like olive oil, coconut oil, or avocado oil).
Don't eat: grains, legumes, dairy, processed foods, sugar, artificial sweeteners, industrial fats and oils.
3. If you work out on a given day, eat whatever you want from 6pm until the start of the overnight fast. Alcohol is also okay, though ideally don't go past two drinks.
4. If you don't work out, keep eating Paleo until the start of the fast. And skip the drinks.
That's it.
Why This Works
One of the main reasons PB6 works is that, unlike most diet approaches, it's simple and flexible enough to be sustained over the long haul—while still building on several research-backed principles.
Intermittent Fasting
Honestly, intermittent fasting is a bit over-hyped. But it does have enough upsides to make it worth including, especially because most people find it actually makes their lives easier, requiring basically zero work once they get into the rhythm of it. Ongoing research has pointed towards promising potential upsides—from increased cellular autophagy (your body's first line of defense against cancers), to better regulation of cholesterol and multiple hormones. However, we've included it mostly because it helps people naturally eat less over the course of the day, making it a painless way to drop unwanted weight.
Paleo
This one also cuts into fad diet territory, but there's solid research backing up the positive impact of a Paleo approach on everything from glucose tolerance to blood pressure and triglycerides. More importantly, a midday stretch of Paleo naturally moves people towards the handful of changes common across all successful, healthy diets: it increases food quality, prevents nutrient deficiencies (biasing sufficient protein, essential fatty acids, and vitamins and minerals), and constrains energy intake to help drop excess body fat.
Habit Reinforcement and Carb/Calorie Cycling
You already know you'd be healthier if you exercised more. The hard part is actually, reliably doing so. Using a given day's workout as the key to "unlock" free eating that evening builds on a large body of research on habit formation to positively reinforce an exercise habit. At the same time, it creates a rhythm of both carb and calorie cycling, increasing your carbohydrate and overall calorie intake at times when you're most likely to use those nutrients to build new muscle, and reducing them when you're more likely to store them as fat instead.
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Common Questions
Won't I get really hungry?
For the first few days, possibly. Hunger is complex, regulated by a variety of physiological, psychological, and environmental cues. However, reliably getting hungry at certain times of day is mostly driven by a pair of hormones (Ghrelin, which increases appetite, and Leptin, which decreases it) tied to your circadian rhythm. If you normally eat breakfast at 8am, those hormones will cue up hunger in preparation, causing your stomach to rumble at 7:30am.
Fortunately, research has shown that both hormones can be quickly retrained to a new schedule. While skipping breakfast might feel rough for two or three days, by the fourth, you likely won't feel hungry in the morning at all. We frequently hear from clients that once they get rolling with PB6, they sometimes forget to eat entirely until mid-afternoon.
What counts as a 'workout'?
Look at your current fitness level and use common sense. If you're at least moderately fit, a "workout" probably entails some kind of focused strength and/or conditioning session, whether in the gym or at home. If you haven't exercised in years, it might just be a 30-minute brisk walk. Either way, it should feel at least sort of hard, and after doing it a bunch of days in a row you should probably feel like you want a day off to recover.
If I work out in the morning, don't I need to eat after?
Maybe. PB6 done "as is" works best if you work out midday (before lunch) or late afternoon (before dinner). If you work out in the morning and don't break your fast until after noon, you have a choice: if you're strictly trying to maximize fat loss, stick with fasting. The "post-workout nutrition window" is indeed a thing, but it's not nearly as brief or impactful as many fitness professionals make it seem. If you're primarily focused on maximizing muscle gain, consider consuming some protein (around 25-35g) shortly after you work out.
Can I really 'eat whatever I want' after 6pm?
Basically, yes—though you'll make faster progress if you're not a total dick about it. The idea here is that if you work out, you have the freedom to eat things that seem delicious after 6pm. However, there's a difference between eating a slice of cheesecake and eating the entire cheesecake. As the old saying goes, the dose makes the poison. So enjoy what's calling to you. But also remember that you can eat whatever you want regularly, so there's no need to go completely overboard on any given night.
Can I put milk or cream in my coffee during the fast?
We think you shouldn't, but mostly because we're coffee snobs who know the correct answer is black. If you want to add a tablespoon or two of milk or cream to your morning coffee, go for it—it's definitely not going to throw off the whole diet.
So I can never eat breakfast again?
No, you absolutely can. We intentionally designed PB6 to be anti-fragile; unlike something like nutritional ketosis, it won't break entirely just because you don't stick to it perfectly. If you mostly follow the rules, you'll get most of the results. Whether you don't want to look rude at a breakfast meeting, don't want to miss out on the great buffet at a hotel on vacation, or just wake up feeling extra ravenous one day, you can still have breakfast occasionally and be totally fine. Just don't do it all the time. (And since breakfast is technically before 6pm, bonus points if you keep it Paleo—say, an omelette plus a side of fruit.)
Wait, isn't this whole thing basically just an elaborate ploy to make me exercise more and eat less?
No shit. But that's kind of the point: the best diet is one you'll actually stick to, and PB6 is designed to make eating less and exercising more feel like the path of least resistance rather than a daily battle of willpower.
What to Expect
By itself, the PB6 diet is surprisingly powerful. If you're carrying excess body fat, we find that most people who follow it strictly lose about a pound a week.
However, there's obviously a ton more you can do to improve your fitness and health, both now and over the long term. Nutrition is just one piece of the puzzle—how you train, how you recover, how you sleep, and dozens of other factors all interact to determine your overall trajectory.
At A3 Health, we take a data-driven approach to all of it: comprehensive biomarker testing, genetic and epigenetic analysis, movement assessments, and AI-powered analysis to build hyper-personalized plans.
But even without all that, PB6 is a solid foundation that works for most people, most of the time.
Give it a shot for a few weeks and see how you feel.